Field of the Invention
The invention relates to wall-hung toilets, and more particularly to the ability of such toilets to bear the weight of the user when in use.
Description of Related Art
Wall hung toilets, such as those typically found in commercial installations and which generally operate with a flushometer valve or similar device, are designed in the United States to meet several functional criteria, notably the ability to completely remove waste when flushed, to thoroughly cleanse the inside bowl walls upon flushing, to exchange and refill water in the bowl for the next use and to support the weight of the user when seated on the bowl. The UPC code for the weight supporting function requires the toilet to bear a minimum of 500 pounds static load for ten minutes without structural failure.
As the world population, particularly in North America where such standards are applied, increases, so that there are an increasing number of overweight or obese people, there is a need in the art for stronger and more robust wall-hung toilets that can sustain an even greater load-bearing level.
In the North American market, a four-bolt configuration, such as that sold by J.R. Smith Manufacturing Co., Inc. (http.jrsmith.com) is generally known as a common carrier system for commercial wall-hung toilets. A typical wall hung support carrier C is shown as Prior Art in FIG. 1. The rear portion of a commercial wall-hung toilet is configured to have four holes through which bolts are used to mount and attach it to the carrier at locations B shown in FIG. 1. Contact with the carrier C is made only at the areas surrounding the bolt holes. The outward extending position of the bowl when mounted places a torque on the carrier. The area of the toilet around the lower two bolts experiences compressive stress as the weight of the bowl and user, when in use, pushes against the carrier. The upper two bolts serve to keep the bowl in contact with the carrier by pulling it towards the wall on which the bowl is installed. When the maximum load-bearing capacity of the bowl is exceeded, structural failure can occur emanating from one of the four bolt hole areas.
An important design feature of wall hung toilet bowls is the back plate, which is the flat-faced rear portion of the bowl that mates with the carrier when the toilet is installed using a carrier system on a wall surface. The typical commercial carriers such as that of FIG. 1 are designed to bear the load of the bowl at only four bolt positions. Although the bowl when mounted on a carrier system might contact the wall through the carrier in some areas, no significant portion of the load is transferred to it. As such, the back plate design is critically important to the load-bearing aspects of the installation. With reference to a prior art wall hung toilet A sold by the Applicant herein shown in FIG. 2, the back plate D must be able to effectively bridge the load of the toilet and seated user across the span between the lower two bolts which are placed through bolt holes F (typically about 12 in. or more). As the trapway and outlet of a wall hung toilet are generally placed along the centerline L-L′ of the bowl (i.e., along the longitudinal midline), existing wall-hung toilets such as that of FIG. 2 tend to concentrate the load on an area near the lower center of the back plate, roughly 50% of the way between the two bolt hole areas. This “upside down T” configuration (see Prior Art FIG. 2 and FIG. 2A) leads to high tensile stress areas and limits the load bearing capability of the design. As shown in FIG. 2, the upside down T is formed by a vector along line L-L′ as it falls roughly halfway along line E-E′. The vector of such stress is also shown in FIG. 2A with reference to a force line along a base G of a prior art wall hung toilet toward face plate D and bolts H.
In view of the above issues, some wall hung toilets in the art use the trapway of the toilet as a primary structural load-transferring feature. Such configurations, therefore, also have an “upside down T” in terms of load bearing design, an example of which is in FIG. 2. Attempts to counteract this issue in the art include overcoming structural weakness by increasing the thickness or size of the back plate of the toilet and/or by adding structural support ribs. This has been successful in most cases in order to meet the 500 pound minimum code requirements. However, such designs are generally not sufficient for achieving higher load-bearing capability and such toilets have not achieved high load levels of 1,000 or more.
There continues to be a need in the art for more and improved ways to enhance the load bearing capacity of wall hung toilets.